A well-known orthodontic technique involves use of rectangular-cross-section arch wires in combination with "edgewise" orthodontic brackets to apply corrective forces to malpositioned teeth. The arch wire fits in mating slots in the brackets which are mounted on the teeth, and bends made in the arch wire before installation distort the resilient wire when installed in the brackets, resulting in restoring forces which urge the teeth toward a corrected position for proper occlusion.
A common problem in orthodontics is the repositioning of a tooth having a root or roots which are generally properly located, but where the body or crown of the tooth is angled labially or buccally (toward the lips or cheeks) or lingually (toward the tongue) out of the ideal dental-arch position. Correction of this kind of problem is important not only for cosmetic reasons, but more importantly to insure proper occlusion and chewing function of the teeth. The force applied in order to correct a forward or rearward tilt of a tooth out of normal alignment is called a torquing force because the force tends to rotate the tooth about a mesiodistal axis through the tooth root.
Edgewise techniques are well suited to the application of torque, but the torquing bends which are formed in the arch wire are awkward and time-consuming to make with conventional pliers, and require considerable manipulative skill if an accurate, reproducable twisting bend is to be achieved. It is particularly difficult to form a twisting bend with conventional pliers without distorting other portions of the arch wire, and such distortion is undesirable in that it may result in the application of tooth-moving forces to teeth which are already correctly positioned. The plier assembly of this invention enables rapid and accurate formation of twisted portions of an arch wire to be used in applying torque to one or more teeth.